Effects of β-glucan from S. cerevisiae on the expression of Casp9, Ccna2 and Sod1 genes in MCF-7 cells

β-Glucans (βG) are polysaccharides widely distributed in nature with chemopreventive properties. The aim of this study was to investigate the effects of βG and the combined treatment with doxorubicin (Dox) on cell viability and mRNA levels of genes involved in cell cycle, apoptosis and antioxidant response. βG was not cytotoxic. The mRNA levels of CCNA2 of cells exposed to β-glucan was upregulated and the exposure to Dox decreased the expression, while the combination led to an upregulation. Modulation of mRNA levels of CASP9 suggest that βG could inhibit promotion and progression steps of carcinogenesis, eliminating neoplastic cells. The upregulation of CCNA2 gene in combined treatment could be occurred due to ability of βG in restoring the cell cycle distribution pattern after treatment with Dox. The upregulation of SOD1 suggests that βG can enhance the intracellular antioxidant defense, reducing the levels of superoxide dismutase induced by Dox. This response could reduce oxidative damage and attenuate tissue damage during chemotherapeutic treatment. Our data suggest that the drug combination may be less effective in killing tumor cells than the treatment with Dox alone. Thus, future studies should carefully consider this effect on indication of βG during chemotherapy